Wells G & H were two municipal wells developed in 1964 and 1967 to supplement the water supply of the City of Woburn. The wells supplied 30 percent of the city's drinking water. In 1979, city police discovered several 55-gallon drums of industrial waste abandoned on a vacant lot near the wells; subsequently these drums were removed. As a result of this discovery, the nearby wells were tested and found to be contaminated. Both of the wells were shut down in 1979 and a supplemental water supply arranged for the city. Five separate properties on the site were found to be the contributing sources of contamination to the aquifer that supplied the water to these two municipal wells.The total Superfund site covers an area of 330 acres. The population of Woburn is approximately 36,600 people. The area surrounding the site is predominantly light industrial and residential. Some nonresidential properties involved in the cleanup are fenced to limit unauthorized access. The site includes commercial and industrial parks, as well as recreational areas and some residential gardens. The Aberjona River flows through the middle of the site. Surface water run-off from the site is directed through drainage systems toward the river and its tributaries.

The groundwater is contaminated with volatile organic compounds (VOCs) including trichloroethylene (TCE) and tetrachloroethylene (PCE). Sediments in the Aberjona River are contaminated with heavy metals such as arsenic. Soil is contaminated with PAHs, polychlorinated biphynels (PCBs), VOCs, and pesticides. People are at risk if they accidentally touch or swallow contaminated groundwater, soil, or sediments in the Aberjona River. The site is located on land that serves as a recharge area for the aquifer from which the Woburn Municipal Wells G & H historically drew water.

The site is being addressed in four stages: immediate actions and three long-term remedial phases focusing on source control and contaminant migration, and cleanup of the aquifer and the Aberjona River.

One of the potentially responsible parties for site contamination secured their own property with a fence and a guard. Drums containing PCB sludge and soil were removed to an approved facility. One of the potentially responsible parties was required to investigate and remove the pure PCE found in a well on their property.

Source Control and Contaminant Migration, Operable Unit 1

Under the 1989 Record of Decision (ROD), EPA's selected remedy included excavating and incinerating 2,100 cubic yards of contaminated soils on site and backfilling the excavated areas; treating additional contaminated soil in place by extracting soil vapors for treatment and pumping contaminated groundwater from the five source areas and removing the contaminants for treatment. Under the 1991 Consent Decree, EPA negotiated with the potentially responsible parties from four of the five source area properties (UniFirst Corporation, W.R. Grace Company, New England Plastics, and Wildwood Conservation source area properties) to design and construct the remedy at each of their properties. Currently, over 540 million gallons of groundwater has been pumped from the contaminated aquifer and treated, and over 4,700 pounds of contaminants have been removed by the treatment systems. Approximately 200 tons of contaminated soil has also been removed from the site. Treatment technologies conducted on site have included UV-chemical oxidation, catalytic oxidation and carbon adsorption. No on-site incineration was ever performed. Only low-level volatile organic contaminants remain in soil. A soil vapor extraction system is being used to treat that soil in-place.
In March 2003, EPA negotiated an Administrative Order by Consent (AOC) with the potentially responsible party for the fifth source area (Olympia Nominee Trust source area property)for the removal of PCB contaminated soils from the Former Drum Disposal Area (FDDA) portion of their property (west side of river). In 2003, Olympia removed 56 cubic yards of soils contaminated with PCBs, and 5 cubic yards of soils contaminated with PAHs (originally identified in the 1989 ROD). In June 2004, EPA negotiated another AOC with the potentially responsible party of the fifth source area for the cleanup of subsurface soils contaminated with TCE. Under the 2004 AOC, TCE contaminated subsurface soils will be treated in place at the Former Drum Disposal Area by injecting sodium permanganate, a material which destroys TCE by chemical reaction (the treatment is also known as in-situ chemical oxidation), monitor the progress of treatment, document successful cleanup, and re-vegetate and grade the treatment area.

Central Area, Operable Unit 2

Three of the five potentially responsible parties agreed to investigate the Central Area and the underlying aquifer. Three industrial properties, known as the Southwest Properties (Murphy Waste Oil property, former Whitney Barrel property, and former Aberjona Auto Parts property), are called out as a focus for additional assessment within the Central Area. In February 2006, EPA prepared and released the revised Southwest Properties Baseline Risk Assessment (Southwest BRA). A summary of the contaminants primarily driving risks at the Southwest Properties are summarized as follows: PCBs, Hydrocarbons and Chlorodanes in soil drive human health risks at the former Whitney Barrel property; PCBs in sediments drive human health risks at the Murphy Wetland (includes portions of Murphy Waste Oil and Whitney Barrel properties) and PCBs, Chromium and Lead drive ecological risks at the Murphy Wetland; and TCE, Vinyl Chloride and 1,1,2-Trichloroethane drive human health risks in groundwater throughout the Southwest Properties. A more detailed description of risks can be found in Section 3, 4 and 5 of the Southwest BRA.

Aberjona River Study, Operable Unit 3

The Industri-plex Superfund Site is situated in North Woburn, approximately 1 mile upstream of the Wells G&H Superfund Site. The two Superfund sites are hydraulically connected by the Aberjona River, which begins in Reading, flows south through the Industri-Plex Site, under Route 128, through Wells G&H Site, and continues south eventually discharging into the Mystic Lakes. EPA completed historical aerial analyses of the Industri-plex Superfund Site Operable Unit 2 (North of Route 128) and Wells G&H Superfund Site Operable Unit 3 Aberjona River Study (South of Route 128) in 1998 and 2002, respectively, and evaluated preliminary sediment and surface water data from Industri-plex to the Mystic Lakes. EPA found that the primary contaminants of concerns in surface water and sediments are metals in both the North and South of Route 128. Based upon this information, EPA decided to merge the Wells G&H OU-3, Aberjona River Study data, with the Industri-Plex OU-2 Multiple Source Groundwater Response Plan (MSGRP), and form one comprehensive RI/FS for the entire river system from the Industri-Plex Site to the Mystic Lakes (approximately 6 miles of river). In September 2004, EPA completed the Wells G&H OU-3 Revised Aberjona River Study Baseline Risk Assessment, which identifies potential human health and ecological risks along Wells G&H 38 acre wetland (River Reach 1) and the former Cranberry Bog (portion of River Reach 2) immediately south of the Wells G&H Site due to potential exposures to sediments contaminated with metals (e.g. arsenic).
In March 2005, EPA completed the Industri-Plex OU-2 (including Wells G&H OU-3) MSGRP RI. This comprehensive RI describes the contamination and risks along the Halls Brook Holding Area (HBHA) and Aberjona River from Industri-Plex Site to the Mystic Lakes, and how contamination is migrating along the river system. The March 2005 RI merged and refined the baseline risk assessments from Industri-plex to the Mystic Lakes along the Aberjona River. The following summarizes the baseline risks presented to the public and environment: Arsenic and benzene (as well as ammonia) plumes beneath the Industri-plex OU-1 Superfund Site boundary (groundwater) may cause future health risks to people who might come in contact with the water (future industrial/ commercial/ construction worker) within Reach 0; Arsenic and benzene (as well as ammonia) plumes from Industri-plex OU-1 contribute to significant environmental risks in the HBHA Pond sediment and deep surface water within Reach 0; High concentrations of arsenic in both surface and deep soils in the Former Mishawum Lake Bed area may cause future health risk to people who come in contact with the soils within Reach 0; High concentrations of arsenic in shoreline sediments in three distinct areas along the Wells G&H Wetland and Cranberry Bog Conservation Area present a current and/or future health risk to people recreating along the shoreline (east side of the 38 acre Wells G&H wetland within Reach 1 near former production well H, west side of the 38 acre Wells G&H wetland within Reach 1 near the railroad tracks and Olympia Source Area Property, and west-central area of the Cranberry Bog Conservation Area within upper Reach 2); and High concentrations of arsenic in deeper interior wetland sediments presents a future risk to people who might come in contact with the sediments (future dredger/ construction worker) within Reach 0 and 1.

In June 2005, EPA prepared and released the Industri-plex OU-2 (including Wells G&H OU-3) Feasibility Study, and Proposed Plan. Public comment period was held and extended from July 1, 2005 - August 31, 2005. In October, EPA prepared and released a Technical Memorandum - Evaluation of Ammonia and Supplemental Soil Data, a Fact Sheet Supplementing the June 2005 Proposed Plan, and re-opened the public comment period from October 20, 2005 to November 18, 2005. Copies of all the above documents are attached below under the "Reports and Studies" links.

On January 31, 2006, EPA prepared and released Industri-plex OU-2 Record of Decision. The major components to the Industri-plex OU-2 remedy include:

• Dredging and off-site disposal of contaminated sediments in the southern portion of the HBHA Pond; dredging and off-site disposal of contaminated near shore sediments at the Wells G&H Wetland and Cranberry Bog Conservation Area; and restoration of all disturbed areas. This component will address sediments posing unacceptable human health risks for near shore sediments and unacceptable ecological risks for the southern portion of HBHA Pond.

• Use of the northern portion of HBHA Pond as a sediment retention area (primary and secondary treatment cells) that will intercept contaminated groundwater plumes (including arsenic, benzene, ammonia, 1,2-dichloroethane, trichloroethene, naphthalene) from Industri-plex OU-1, treat/sequester contaminants of concern (including arsenic, benzene, ammonia), and minimize downstream migration of contaminants (including arsenic, benzene, ammonia). The primary treatment cell will intercept the contaminated groundwater plumes discharging in the HBHA Pond. The effluent from northern portion of the HBHA Pond (secondary treatment cell outlet) will serve as the surface water compliance boundary, and achieve National Recommended Water Quality Criteria (NRWQC). Sediments which accumulate in the northern portion of the HBHA Pond will be periodically dredged and sent off-site for disposal. Portions of storm water from Halls Brook, which may interfere with the natural treatment processes occurring within the northern portion of the HBHA Pond, will be diverted to the southern portion of HBHA Pond.

• Construction of an impermeable cap to line stream channels (e.g. New Boston Street Drainway), and to prevent the discharge of contaminated groundwater plumes, contamination of stream sediments, downstream migration of contaminants of concern, and potential impacts to other components of the selected remedy.

• Construction of a permeable cap to prevent contaminated soil erosion (e.g. Area A6), downstream migration of contaminants of concern, and potential impacts to other components of the selected remedy.

EPA signed a Consent Decree with the potentially responsible parties in 1991. Four potentially responsible parties agreed to conduct the remedy at their respective properties (addressing four of the five source area properties at the Site). Three of the potentially responsible parties agreed to conduct a study of contamination in the aquifer beneath the Central Area of the site and to assess if other sources exist.
The potentially responsible party for the fifth source area removed 12 and 5 drums under Administrative Orders by Consent (AOC) in 1986 and 1987, respectively. This area of the property is known as the Former Drum Disposal Area (FDDA). In 2003, the potentially responsible party removed approximately 56 cubic yards of PCB contaminated soils from the FDDA under a third AOC, as well as approximately 5 cubic yards of soils contaminated with PAHs. In 2004, the potentially responsible party implemented an EPA approved work plan to treat subsurface soils contaminated with TCE at the FDDA under a fourth AOC.

In September 2006, EPA issued special notice letters to potentially responsible parties for the cleanup of Industri-plex OU-2 (including Wells G&H OU-3) in accordance with the January 2006 Record of Decision. In February 2008, EPA and U.S. Department of Justice lodged the Industri-plex OU-2 Consent Decree with Bayer CropScience and Pharmacia Corporation. On November 24, 2008, U.S. District Court entered the Industri-plex OU-2 Consent Decree.

Millions of gallons of contaminated groundwater has been cleaned up. Tons of contaminated soil has been removed from the site for treatment. Treatment of groundwater and low-level soil contamination continues. Fencing of one portion of the Wells G & H site has reduced the potential for exposure to hazardous materials at the site while final cleanup activities are being conducted.

Source Control and Contaminant Migration: Remedial action is well underway in Operable Unit 1. Three groundwater pump-and-treat systems draw contaminated groundwater from the aquifer at three of the source area properties. Two of the systems (UniFirst and W.R. Grace source area properties) are in their eighteenth year of operation and treat groundwater using carbon adsorption. The third system (Wildwood Conservation Corporation (Wildwood) source area property), in its twelfth year of operation, uses a combined pump-and-treat/air sparging/ soil vapor extraction system with carbon adsorption treatment. Another soil vapor extraction system was operated at the fourth source area property (New England Plastics (NEP)) for over a year and successfully cleaned up contaminated soil. Groundwater in that area is being monitored to determine if additional cleanup is needed. In addition to the continuation of cleanup at these four source area properties, PCBs and PAHs contaminated soils were removed from the fifth source area property in 2003. In 2004, EPA reached an agreement with the owner of the fifth source area property (Olympia Nominee Trust (Olympia)) to cleanup subsurface soils contaminated with TCE at the Former Drum Disposal Area of the property. This TCE subsurface soil cleanup continues today. In May 2009, EPA issued draft comments to the WR Grace, UniFirst, NEP and Wildwood source area properties to optimize cleanup efforts. In September 2009, EPA also completed a Five Year Review of the remedy selected under the 1989 ROD that deferred a statement of protection until addition data is collected near the WR Grace, UniFirst and NEP source area properties. The Settling Defendants are working cooperatively with EPA to address concerns outlined in the May 2009 draft comments and September 2009 Five Year Review Report. In 2010, the Settling Defendants installed shallow monitoring wells near the WR Grace, UniFirst and NEP source area properties to initially evaluate groundwater quality and the potential pathway for vapor intrusion (release of vapors from groundwater upwards towards buildings). In January 2011, EPA released the shallow groundwater results and recommended additional sampling in some buildings near two of the source area properties to evaluate potential risks from intrusion of vapors. In 2011, the Settling Defendants collected two rounds of indoor air and sub-slab soil gas samples from various buildings near UniFirst and WR Grace Source Area properties. In 2012, EPA prepared a Five Year Review Addendum (April 2012) and determined the remedy for operable unit 1 to be protective of human health and the environment. The Five Year Review Addendum concluded: no vapor intrusion pathway risk to nearby residential and commercial properties; continue annual indoor air and sub-slab soil gas sampling at commercial building adjacent to UniFirst Source Area property; expand annual groundwater monitoring by Grace and UniFirst Source Area properties, and design and implement the In-situ Soil Volatilization remedy at UniFirst Source Area property. In summer 2012, 894 tons of soils above the cleanup action levels were removed from WR Grace Source Area Property, as documented in the "Soil Response Action Completion Report," dated July 3, 2013. In May 2014, UniFirst designed the SVE system (dated May 1, 2014), and installed and began SVE operations in November 2014. The UniFirst SVE system continues to operate. In support of future reuse of the WR Grace Source Area property, EPA approved a Soil and Groundwater Management Plan in April 2015 which will help ensure the remedy remains protective during redevelopment.

Central Area Aquifer: In February 2006, EPA prepared and released the revised Southwest Properties Baseline Risk Assessment (BRA). In May 2009, EPA issued draft comments to the Settling Defendants outlining the additional data needs and RI/FS progress at the Central Area and Southwest Properties. The Settling Defendants are working cooperatively with EPA to address concerns outlined in the May 2009 draft comments regarding the Southwest Properties. In November 2010, EPA approved a work plan for the Settling Defendants to conduct a focused Supplemental Remedial Investigation at the Southwest Properties. In March 2014, EPA released a final baseline risk assessment for the Southwest Properties. EPA anticipates finalizing the RI/FS in 2015. EPA anticipates further Central Area coordination in 2015.

Aberjona River Study: EPA merged Wells G&H OU-3 Aberjona River Study with the Industri-plex OU-2 comprehensive RI/FS from Industri-plex to the Mystic Lakes. In January 2006, EPA prepared a Record of Decision for Industri-plex OU-2 (including Wells G&H OU-3 Aberjona River Study). In February 2008, EPA and U.S. Department of Justice lodged the Industri-plex OU-2 Consent Decree with Bayer CropScience and Pharmacia Corporation. On November 24, 2008, U.S. District Court entered the Industri-plex OU-2 Consent Decree. In January 2009, EPA approved the Industri-plex OU-2 Surface Water Monitoring Plan. On March 24, 2011, EPA approved the Industri-plex OU-2 Remedial Design Work Plan. Currently, the Industri-plex OU-2 Settling Defendants implemented Lower South Pond sediment removal and restoration in 2014, will implement 100% RD Part 1 in 2015 and 2016, implement 100% RD Part 2 in 2016. (See also the Industri-Plex site)